Workers in the art of designing and using computer modules and like arrangements are aware that often a plurality of printed circuit cards must be mounted, side-by-side, in a card rack such as rack R in FIG. 2, and cooled there. FIG. 1 shows, in very schematic fragmentary side-view, a computer unit 1, characterized by three card racks R-1, R-2, R-3 each including upper input-plenum means (respectively P.sub.1, P.sub.2, P.sub.3) adapted to receive input coolant air, e.g., pumped-in from outer inlet (cf. "AIR IN"), urge it down through its set of printed circuit cards (arrows, FIG. 1) to exit the rack and the machine (cf. "AIR OUT").
FIG. 1A shows, in schematic fragmentary perspective, one of the card racks R with three plenum means P (arrows show coolant path), it being understood that an array of printed circuit cards (e.g., as card pc in FIG. 1D) are to be stacked in parallel alignment, each engaged between respective upper and lower channels ch. Two exemplary lower channels ch-1, ch-2 are depicted in part in FIG. 1B, each comprising a spaced pair of guides or walls (g.sub.1, g.sub.1 ' and g.sub.2, g.sub.2 ') joined by an intermediate base (B.sub.1, B.sub.2 joined by side segment SD, FIG. 1B). For instance, guides g may be formed by cutting and bending a single sheet metal piece (SD, FIG. 1B) so that, for instance, g.sub.1 ', g.sub.2 are cut and bent-up out of a slot SLL (FIG. 1B) through which the coolant air is to pass (as known in the art). Thus, the bases (e.g., B.sub.1, B.sub.2) and connecting side segments SD extend along a relatively flat common plane (pl, FIG. 1C) out of which the like guides g are raised. For various reasons, the guides are formed to diverge slightly in the "up-direction", e.g., in FIG. 1C, guides g, g', of height hg diverge a few degrees, being spaced about 100-120 mils apart at their base (plane pl, base-width ch-w). So, a pc board wedged-in between guides g, g' is apt to engage them for only a portion of their height hg (as with PC, cf. width ch-w, in FIG. 1B--here assume a like upper channel ch').
FIG. 1D shows, in schematic perspective, a typical printed circuit card PC, comprising a circuit-board Bd with connector pins cc at one end and enlarged head or handle means h at the other. The head will span its respective channel slot when fully-inserted in a slot, and so block egress of coolant-air from within rack R. Each of the relatively planar circuit boards PC is inserted from one side of the rack (note "IN" side of R) in respective "slots" defined between receiving upper and lower channel means Ch, Ch', being thrust between the channel guides g, g' defining each channel (e.g., see PC in FIG. 1C) snugly to be relatively firmly secured at the opposite (back) end of the rack where they are typically lodged in a connector pin array, etc. (cf. FIG. 1D, pc connectors cc engaged by back panel connector B-cc and held in channels ch, ch'). FIG. 1B schematically illustrates (fragmentarily) a part of a typical channel Ch defined between a pair of like spaced guides g, g', projected from a common base plane pl to be projected a prescribed height hg thereabove.
As workers know, heat dissipation from such a closely-packed array of boards (PC) can be a problem unless supplemental cooling means is supplied, such as forced air, or a like gaseous draft, as indicated by the arrows in FIGS. 1, 1A--the coolant gas being entrained, for instance, down along both sides of all the cards (from top to bottom, here). Typically, rack R will be enclosed within some cabinet means, such as a computer chassis (as FIG. 1) wherein the entrained air may be kept at a positive pressure (above ambient; e.g., with an intake and fan means above each rack, as workers in the art appreciate). A typical card PC is shown in FIG. 1D and discussed above.
It will be apparent that, unless all the "slots" in a rack are filled with cards, and the cards thrust-in fully to block egress of coolant-air, such air will escape. Thus, if heads h of a PC array filling all slots in rack R (FIG. 1A) are disposed in contiguous abutment across the entry plane "IN" of rack R, the pressurized coolant air within is kept from escaping--otherwise an air-leak may radically degrade, if not destroy, the inner over-pressure and interfere with necessary cooling. (For instance, see adjacent heads h.sub.1, h.sub.2, h.sub.3 in FIG. 1E and discussion thereof below).
Thus, when any given card PC is withdrawn from a full set in rack R, the body of pressurized air should still be kept up to pressure within the rack by substitution of what workers call an "air seal" (e.g., see AS in FIG. 1A). An "air seal" typically comprises a replica of enlarged head means h along with associated attachment means for gripping the guides g, g' of both channels Ch. As workers well know, it is problematic to manufacture such "air seals" inexpensively and efficiently and so they exhibit precise dimensional and shape tolerances; e.g., so they are configured with sufficient precision to assure insertion and retention in any slot, willy-nilly, without some "play" that allows pressurized air to escape. This invention is directed toward improved "air seals".
This problem is exacerbated, of course, by attempts to standardize the design and manufacture of a card rack R from sheet metal stock (cf. using inexpensive material and methods, e.g., to form the channel pairs ch, ch'). For instance, the guides g, g' making up each channel can obviously vary in size, shape, spacing, etc.--though each channel must snugly receive any card and its associated head, as well as any and all "air seals", however fabricated.
This problem is even further aggravated when the channel guides g, g' are made relatively shallow (cf. reduced height hg thereof, FIG. 1C).
This invention is intended to develop methods and means for addressing such problems and features, e.g., for improving such air seals so they are better adapted for such sheet metal card racks where the depth of the card guides is minimal, and to particular methods and arrangements for better retaining air seals in such guides.
This invention is further intended to provide improved means for retaining air seals in a sheet metal card rack adapted for a computer processor and/or an associated I/O chassis, particularly where the air seal includes molded plastic spring means thrust against the bases from which the card guides are projected, wherein such spring means are adapted to so engage such bases as to provide superior frictional retention of the air seal. This invention is thus adapted to provide a more positive, more reliable engagement and retention of air seals in shallow card guides. More particularly this invention is adapted to provide engagement-forces normal to such a guide-base, rather than relying only on lateral (side-to-side) forces, directed parallel to the plane of the guide-base.